JP2005503552A - Equipment for testing aramid fiber elevator cables - Google Patents

Abstract

The present invention is an apparatus for inspecting an aramid fiber cable (7) driving an elevator (3) and calculating a residual strength of the aramid fiber cable (7), whereby the replacement of the cable (7) can be performed. The present invention relates to an inspection and calculation device for obtaining a necessary time. The apparatus comprises a transmitter (22) that transmits sound waves traveling along an aramid fiber cable (7) and a receiver (24) that receives the sound waves after the sound waves have traversed a designated portion of the cable (7). The transmitter (22) and the receiver (24) supply a signal indicating the time when the sound wave is transmitted by the transmitter (22) and a signal indicating the time after which the sound wave is received by the receiver (24). From these signals, the system program calculates the wave velocity, the elastic modulus of the aramid cable (7), and the residual strength of the aramid cable (7).

Description

【Technical field】
[0001]
The present invention relates to an elevator system. More particularly, the present invention relates to an apparatus for testing an aramid fiber cable to determine when the aramid fiber cable used in an elevator system is damaged and needs to be replaced.
[Background of the invention]
[0002]
Conventional steel cables for elevators can be easily visually inspected for wear. Since the wires break individually, these breaks can be easily confirmed. Aramid fiber elevator cables are covered with a protective sheath that makes visual inspection impossible. Even when the rope is not armed, it may be difficult to determine a suitable time to change the rope. This is because the appearance of the fiber is almost the same regardless of whether the fiber is new or needs to be replaced.
[0003]
U.S. Pat. No. 5,834,942 issued to De Angelis on Nov. 10, 1998 discloses an apparatus for determining when a synthetic fiber cable for an elevator (such as an aramid cable) should be replaced. The apparatus includes a voltage detection device that detects a voltage on at least one carbon fiber of the synthetic fiber cable and at least one threshold device that determines when the detected voltage exceeds a predetermined voltage threshold. The detected voltage depends on the integrity of a portion of the synthetic cable (especially the carbon fibers in the synthetic cable). Exceeding the predetermined voltage threshold indicates failure of that portion of the cable. Prior art devices take the measure of placing conductive fibers in the cable so that the fibers can be monitored by electrical means. Therefore, this device may not be suitable for synthetic cables that are not readily conductive.
[0004]
Those skilled in the art have shown that elastic properties of aramid materials can be determined from measurements of wave propagation through the aramid material (M. Ferreira et al., “Nondestructive Testing of Polyaramide Cables by Longitudinal Wave Propagation: Study of the Dynamic Modulus ”, Polymer Engineering and Science, Vol. 40, No. 7, July 2000). In particular, it has been found that polyaramid cables in different fatigue states each have their own acoustic longitudinal wave velocity. Longitudinal waves are known to travel on aramid fiber ropes according to the following formula:
V ² = E / ρ (Formula 1)
Where V = velocity of wave propagation, E = dynamic or sonic modulus, and ρ = density. The tensile modulus and acoustic modulus both change at the same rate with fatigue, so the tensile modulus can be calculated from the observed wave propagation values. It was found that E = f (Fr), where E (elastic modulus) is plotted against Fr (residual strength). In other words, there is a quantifiable relationship between the elastic modulus (obtained from the velocity) and the residual strength.
[0005]
For an aramid cable used in an elevator system, a similar relationship can be obtained between elastic modulus and residual strength. This relationship varies based on the particular aramid material used in the cable and the dimensions of the cable. It is possible to extrapolate the residual strength from a plurality of measurements of modulus of elasticity where the relationship is determined. This has not been done so far for elevator systems.
[0006]
Accordingly, it is an object of the present invention to provide an apparatus for inspecting an aramid fiber elevator cable and calculating the residual strength of the cable in order to determine when the cable needs to be replaced.
[Summary of Invention]
[0007]
The present invention relates to an apparatus for inspecting an aramid fiber cable that drives an elevator and calculating the residual strength of the cable, thereby determining and calculating the time when the cable needs to be replaced. The apparatus comprises a transmitter that transmits sound waves traveling along an aramid fiber cable and a receiver that receives the sound waves after the sound waves have traversed a designated portion of the cable. The transmitter and the receiver supply a signal indicating the time when the sound wave is transmitted by the transmitter and a signal indicating the time when the sound wave is subsequently received by the receiver.
[0008]
The present invention provides a means for processing the first signal and the second signal, thereby calculating the residual strength of the cable. In particular, the present invention provides an elevator control system connected to a transmitter and a receiver. The control system has a program and associated algorithm that calculates the velocity of the sound wave based on the time of the first signal and the second signal. In this case, the program calculates the elastic modulus of the cable and subsequently determines the residual strength of the cable. Determining the residual strength is based on a stored equation that indicates the residual strength as a function of the modulus of elasticity. The stored formula depends on the specific aramid cable used in the system.
[0009]
The transmitter and receiver may be placed at various locations along the cable. However, in a preferred embodiment, the transmitter and receiver are co-located along the cable and located a nominal distance from the sheave used in the elevator system. In this case, the speed of the sound wave is calculated by measuring the time it takes for the sound wave to travel from the transmitter to the sheave and back to the receiver. In this embodiment, the transmitter and receiver are actually housed in one unit.
[0010]
The invention also relates to an elevator system incorporating an apparatus for inspecting an aramid cable used to drive the elevator system. The elevator system typically includes an elevator car, an aramid fiber cable connected to the car, a hoist with a drive motor that moves the cable to move the car, and one or more to guide the movement of the cable. A sheave and a counterweight coupled to the cable to balance the weight of the car. The device of the present invention is incorporated into this system.
Detailed Description of the Invention
[0011]
1 and 2 show the present invention embodied in two different elevator systems. In these figures, like reference numerals represent like elements.
[0012]
The system comprises an elevator car 3 suspended by an aramid fiber cable 7. The aramid fiber cable rests on one or more sheaves 9 and is connected to a counterweight 11 to keep the system balanced. A hoisting machine 15 including one of the sheaves 9 drives the cable in one of two directions to raise and lower the elevator car 3.
[0013]
The apparatus of the present invention is incorporated into the system as follows. Referring to the enlarged views of FIG. 1A and FIG. 2A, a transmitter 22 and a receiver 24 each composed of an acoustic sensor are connected to the aramid fiber cable 7. The transmitter 22 includes components that can transmit acoustic waves along the aramid fiber cable 7. The transmitter 22 transmits sound waves that travel from the transmitter to the nearest sheave and reflect back from the sheave to the receiver 24. The transmitter 22 and the receiver 24 generate a signal indicating the time when the sound wave is first transmitted to the cable 7, and then a signal indicating the time when the sound wave is received by the receiver 24.
[0014]
Means are provided for processing the first signal and the second signal, thereby calculating the residual strength of the cable. In particular, the present invention provides an elevator control system 35 that is connected to both the transmitter 22 and the receiver 24. The control system 35 has a program that includes an algorithm suitable for calculating the velocity of the sound wave based on the first signal and the second signal. The control system and program may be provided in the machine room (as in FIG. 1). In addition, as shown in FIG. 2, the elevator car 3 may include an interface 38 that receives signals from the transmitter and receiver and sends the signals to the control system. A program in the control system calculates the cable's modulus, and then determines the cable's residual strength from a stored equation that represents the residual strength as a function of the modulus.
[0015]
When the calculated residual strength falls below a predetermined threshold, the control system 35 suitably gives notification that the aramid cable 7 needs to be replaced. If desired, the control system may be programmed to shut down the system when the residual strength of the aramid cable 7 falls below a threshold value. Residual strength values are determined periodically and can be automatically stored in the memory of the control system for use in predicting cable life. This is an important advantage since the cable can be tested to determine the residual strength while the elevator is running. In particular, the device of the present invention can continuously test the residual strength of the cable, which can be done by testing various parts of the cable during elevator operation. By testing various parts of the cable while the elevator car is located at various locations in the system, the apparatus of the present invention can ultimately test the total length of the cable. One particular option in this regard is that the device evaluates the entire cable by incrementally testing various successive portions of the cable. Another option may be to randomly test various parts.
[Brief description of the drawings]
[0016]
FIG. 1 shows the present invention embodied in a first elevator system.
FIG. 1A shows an enlarged view of the receiver and transmitter shown in FIG.
FIG. 2 shows the present invention embodied in a second elevator system.
FIG. 2A shows an enlarged view of the receiver and transmitter shown in FIG.

Claims (12)

An apparatus for inspecting and calculating an aramid fiber cable driving an elevator and calculating a residual strength of the aramid fiber cable, thereby obtaining a time when the cable needs to be replaced;
Transmitting a sound wave along the aramid fiber cable (introduce) and supplying a first signal indicating the time when the sound wave was transmitted;
A receiver for receiving the sound wave traveling along the aramid fiber cable and supplying a second signal indicating a time when the sound wave is received;
Means for processing the first signal and the second signal, thereby calculating and processing the residual strength of the cable;
A device comprising: The means for processing the first signal and the second signal includes an elevator control system connected to the transmitter and the receiver, the control system comprising the first signal and the second signal. The apparatus according to claim 1, further comprising: a program and an associated algorithm for calculating the speed of the sound wave, the elastic modulus of the cable, and the residual strength of the cable by processing the time of The apparatus of claim 2, wherein the transmitter and receiver are located at different locations along the cable. The apparatus of claim 2, wherein the transmitter and receiver are co-located along the cable. The apparatus of claim 2, wherein the transmitter and receiver comprise a unit. An elevator system,
An elevator car, an aramid fiber cable connected to the car, a drive motor that moves the cable to move the car, one or more sheaves that guide the movement of the cable, and balance the weight of the car A counterweight connected to the cable to take;
An apparatus for inspecting and calculating the residual strength of the aramid fiber cable by inspecting the aramid fiber cable, thereby obtaining a time when the cable needs to be replaced,
A transmitter for transmitting a sound wave traveling along the aramid fiber cable and supplying a first signal indicating a time at which the sound wave is transmitted;
A receiver that receives the sound waves traveling along the aramid fiber cable and supplies a second signal indicating the time at which the sound waves in progress are received, and processes the first signal and the second signal Means for calculating and processing the residual strength of said cable,
An apparatus comprising:
Elevator system with The means for processing the first signal and the second signal includes an elevator control system connected to the transmitter and the receiver, the control system comprising the first signal and the second signal. 7. An elevator system according to claim 6, comprising a program and an associated algorithm for calculating the velocity of the sound wave, the elastic modulus of the cable, and the residual strength of the cable based on The elevator system of claim 7, wherein the transmitter and receiver are located at different locations along the cable. 8. The elevator system of claim 7, wherein the transmitter and receiver are co-located along the cable, and the sound waves travel from the transmitter to the sheave and reflect back to the receiver. . The elevator system according to claim 7, wherein the transmitter and the receiver constitute one unit. The apparatus is adapted to calculate residual strength of various portions of the length of the aramid fiber cable when the elevator is in operation and at various locations in the system. The elevator system described in. The elevator system according to claim 11, wherein the apparatus is adapted to calculate in stages the residual strength of various parts of the aramid fiber cable, thereby evaluating the entire cable.

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